JP2636626B2 - Silicone rubber composition and cured product - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a silicone rubber composition which gives a cured product having a high tensile strength and a high tear strength.

[0002]

2. Description of the Related Art Silicone rubber has excellent properties such as electrical insulation, heat resistance, cold resistance and weather resistance, and is used in various fields.
It had a drawback that it was inferior to other rubber materials in tensile strength and tear strength.

[0003] In order to solve this problem, there have been proposed improvement measures such as blending a treated filler into the silicone rubber composition or blending a polymer having a localized functional group. However, a cured product having higher tensile strength and tear strength has been proposed. There is a need for silicone rubber compositions that provide

[0004] The present invention has been made in view of the above circumstances,
An object of the present invention is to provide a silicone rubber composition that gives a cured product having high tensile strength and high tear strength, and a cured product thereof.

[0005]

The present inventors have made intensive studies to achieve the above object, and as a result, as a siloxane component, a silicone rubber composition containing a base siloxane component, a filler, and a curing agent. The present inventors have found that a silicone rubber composition that gives a cured product having extremely high tensile strength and tear strength can be obtained by blending the organopolysilalkylenesiloxane represented by the following general formula (I). Reached.

[0006]

Embedded image

Accordingly, the present invention provides a silicone rubber composition comprising (A) the organopolysilalkylenesiloxane of the above formula (I), (B) a filler and (C) a curing agent, and A cured product obtained by curing is provided.

Hereinafter, the present invention will be described in more detail. In the silicone rubber composition of the present invention, an organopolysilylalkylenesiloxane represented by the following general formula (I) is blended as a base siloxane component (component (A)). I do.

[0009]

Embedded image

Here, R ¹ , R ² , R ³ , R ⁴ and R ⁵ are the same or different unsubstituted or substituted monovalent hydrocarbon groups containing no aliphatic unsaturated groups, preferably carbon atoms. Number one
To 8, which may be the same or different.

Specifically, alkyl groups such as methyl group, ethyl group and propyl group; cycloalkyl groups such as cyclohexyl group; aryl groups such as phenyl group and tolyl group;
3,3,3-trifluoropropyl group, 6,6,6
A group in which a hydrogen atom of these groups such as 5,5,4,4,3,3-nonafluorohexyl group, chloromethyl group, and 3-chloropropyl group is partially substituted with a halogen atom, 2-cyanoethyl Examples include a cyano hydrocarbon group such as a group, and particularly preferred are a methyl group, an ethyl group, a phenyl group, and a 3,3,3-trifluoropropyl group. R ⁶ is a monovalent aliphatic unsaturated hydrocarbon group, for example, a vinyl group, an allyl group, an ethynyl group and the like, and among them, a vinyl group is preferable.

X is a hydrogen atom or the following general formula (I)
It is a group represented by I).

[0013]

Embedded image ^{(Wherein, R 7, R 8, R} 9 is an unsubstituted or substituted monovalent hydrocarbon groups, respectively, such as a hydrocarbon group having no exemplified aliphatic unsaturated bond as R ¹ to R ⁵ described above, a vinyl group, Alkenyl groups such as an allyl group and a hexenyl group, which may be the same or different from each other.)

Such X is, for example, a hydrogen atom,
_{(CH 3) 3 Si -,} (CH 2 = CH) (CH 3) 2 Si-
Etc. are preferably used.

N is an integer of 1 or more, preferably 10
M is an integer of 0 to 10,000, m is an integer of 0 or more, a
Is an integer of 4 to 16. As understood from the values of n and m, the organopolysilalkylene of the above formula (I) does not include the structural unit represented by the following formula as an essential structural unit.

[0016]

Embedded image

The organopolysilalkylenesiloxane of the above formula (I) can be produced by a known method.
In this case, in the above formula (I), those in which X is a hydrogen atom, that is, those in which the molecular chain terminal is a silanol group are, for example, an organosylalkylenesiloxane represented by the following general formula (III) and the following general formula (IV) Can be synthesized by copolymerizing a diorganosiloxane represented by the formula (1) in the presence of an alkali or acid catalyst.

[0018]

Embedded image

The organopolysilalkylenesiloxane of the above formula (I) in which the molecular terminal is blocked by a group represented by the above general formula (II) can be prepared by the following general formula (V) or It can be produced by performing copolymerization in the presence of the silicon compound represented by (VI).

[0020]

Embedded image

Examples of the alkali or acid catalyst used in the copolymerization include alkali hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide, alkali siliconates such as lithium siliconate and potassium siliconate, and tetrabutyl. It is derived from quaternary salt hydroxides such as phosphine hydroxide and tetrabutylammonium hydroxide, sulfonic acids such as sulfuric acid and trifluoromethanesulfonic acid, trifluoroacetic acid, and hexafluoropropene oxide oligomer represented by the following general formula. Examples thereof include a fluorinated carboxylic acid.

[0022]

Embedded image

In this case, the amount of the alkali or acid catalyst to be added is preferably 0.01 to 5 parts by weight, more preferably 0.05 to 1.0 part by weight, per 100 parts by weight of the siloxane. The mixing ratio of the starting materials is not particularly limited, but can be as follows, and the reaction temperature is 90 to 150 ° C., particularly 12
The temperature is preferably set to 0 to 150 ° C.

[0024]

Embedded image

In the present invention, a filler is used as the component (B) in addition to the organopolysilalkylenesiloxane as the component (A). Here, as the filler, various fillers used in general silicone rubber compositions can be used, for example, fumed silica, precipitated silica, carbon powder, titanium dioxide, aluminum oxide, quartz powder, Reinforcing fillers such as talc, sericite, bentonite and the like, and fibrous fillers such as asbestos, glass fiber and organic fiber are exemplified.

In the present invention, these fillers are usually
It is preferable to mix 10 to 300 parts by weight, particularly 20 to 200 parts by weight, per 100 parts by weight of the component (A). When the amount of the filler is less than 10 parts by weight,
In some cases, a sufficient reinforcing effect cannot be obtained, and when it is added in a proportion exceeding 300 parts by weight, there is a possibility that the mechanical strength of the cured product may be reduced.

In the silicone rubber composition of the present invention, the curing agent used as the component (C) includes, for example, an organic peroxide and an organo having at least one hydrogen atom bonded to a silicon atom in the molecule. Hydrogen polysiloxane and the like are preferably used.

As the organic peroxide, various ones used for organic peroxide crosslinking can be used. For example, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, 4-monochlorobenzoyl peroxide, Dicumyl peroxide, tert-butyl benzoate, tert-butyl peroxide, 2,5
-Dimethyl-2,5-bis (tert-butylperoxy) hexane, cumyl-tert-butyl peroxide and the like can be used alone or in combination of two or more.

On the other hand, examples of the organohydrogenpolysiloxane having at least one hydrogen atom bonded to a silicon atom in the molecule include the following. In the following formula, Me is a methyl group, Ph is a phenyl group, and Pr is a propyl group.

[0030]

Embedded image

The compounding amount of such a curing agent is generally from 0.2 to 10 parts by weight based on 100 parts by weight of the component (A). The amount is preferably in the range of 0.2 to 5 parts by weight per 100 parts by weight of component (A), and in the case of the above-mentioned organohydrogenpolysiloxane, it is preferably in the range of 0.5 to 10 parts by weight per 100 parts by weight of component (A). It is. When an organohydrogenpolysiloxane is used, a known platinum-based catalyst can be blended.

In the silicone rubber composition of the present invention, it is possible to add various additives in addition to the above-mentioned essential components as long as the object of the present invention is not impaired. For example, dispersants such as diphenylsilanediol, dimethylpolysiloxane having a low degree of polymerization and capped with hydroxyl groups at the molecular chain terminals, and hexamethyldisilazane; heat-resistance improvers such as ferrous oxide, ferric oxide, cerium oxide, and iron octylate; A coloring agent such as a pigment can be blended as required. .

The silicone rubber composition of the present invention can be easily prepared by uniformly kneading the above-mentioned components using a mixer such as a roll, a kneader, or a Banbury mixer.

This silicone rubber composition is subjected to a heat treatment at a temperature of 100 to 200 ° C. for 30 seconds to 1 hour under normal pressure or pressure, and if necessary, a secondary vulcanization at a temperature of 150 to 200 ° C. for 2 to 24 hours. By doing so, it is completely cured and becomes a cured silicone rubber rich in elasticity.

[0035]

The silicone rubber composition of the present invention provides a cured product having high tensile strength and high tear strength.
The rubber material can be effectively used for applications requiring these properties, such as rubber materials for packing and sealing.

[0036]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

Example 1 A 1-liter four-necked flask equipped with a stirring rod, a nitrogen inlet tube, a thermometer and an exhaust tube was charged with a silalkylenesiloxane 600 represented by the following formula (1).
g, a diorganosiloxane represented by the following formula (2):
6g and 0.3g of potassium siliconate were charged and 100
After heating and stirring at 3 ° C. for 3 hours, a raw rubber-like polymer (organopolysilalkylenesiloxane represented by the following formula (3)) was obtained.

[0038]

Embedded image

Next, the following components are kneaded with a kneader,
Heat treatment was performed at 105 ° C. for 4 hours.

The above polymer (organopolysilalkylene siloxane) 100 parts by weight Fumed silica (specific surface area 200 m ² / g) 40 {diphenylsilanediol 3.9} Viscosity 20 cs, both ends of molecular chains are blocked by hydroxyl groups. 3.9} Further, 100 parts by weight of the above kneaded material, 2,5-dimethyl-
2,5-bis (t-butylperoxy) hexane 0.4
The parts by weight were uniformly mixed using two rolls to obtain a composition I.

The composition I was heated at a temperature of 140 ° C. and a pressure of 120
The sheet was pressed under the condition of kg / cm ² for 20 minutes to form a sheet having a thickness of 2 mm, and then heat-treated at 140 ° C. for 4 hours.

Comparative Example 1 For the purpose of comparison, a composition II was prepared in the same manner as described above except that dimethyl silicone raw rubber was used instead of the organopolysilalkylenesiloxane. This composition II was heated at a temperature of 170 ° C and a pressure of 120k.
After pressing under a condition of g / cm ² for 20 minutes to form a sheet having a thickness of 2 mm, the sheet was further heated at 200 ° C. for 4 hours.

When the physical properties of the sheets obtained in Example 1 and Comparative Example 1 were examined, the results shown in Table 1 were obtained.

[0044]

[Table 1]

From the results shown in Table 1, the silicone rubber composition of the present invention (Example 1) has a 1.8 times tensile strength and 2.1 times the tear strength as compared with the silicone rubber composition of Comparative Example 1. It was confirmed that a cured product having high strength and high tear strength was provided.

Example 2 A 1-liter four-necked flask equipped with a stirring rod, a nitrogen inlet tube, a thermometer and an exhaust tube was charged into a 1-liter silalkylenesiloxane 200 represented by the above formula (1).
g, a diorganosiloxane represented by the above formula (2).
32 g, 1,3-divinyl-1,1,3,3-tetradimethylsiloxane 0.05 g and potassium siliconate 0.05 g were charged and heated and stirred at 150 ° C. for 3 hours to obtain a raw rubber-like polymer (the following formula). An organopolysilalkylenesiloxane represented by (4)) was obtained.

[0047]

Embedded image

Next, the following components are kneaded in a kneader,
Heat treatment was performed at a temperature of 120 ° C. for 4 hours.

100 parts by weight of the above polymer fumed silica (specific surface area: 200 m ² / g) 42 {diphenylsilanediol 4} Further, 100 parts by weight of the above kneaded product, 2,5-dimethyl-
2,5-bis (t-butylperoxy) hexane 0.4
Parts by weight using a two-roll mill, and
I was obtained.

A 2 mm-thick sheet of the composition III was prepared from this composition III in the same manner as in the composition I of Example 1.

Example 3 In a 1-liter four-necked flask equipped with a stirring rod, a nitrogen inlet tube, a thermometer and an exhaust tube, a silalkylenesiloxane 300 represented by the above formula (3) was placed.
g, a diorganosiloxane represented by the above formula (2).
44 g, 1,3-divinyl-1,1,3,3-tetradimethylsiloxane 0.06 g and potassium siliconate 0.06 g were charged and heated and stirred at 150 ° C. for 3 hours to obtain a raw rubber-like polymer (the following formula). An organopolysilalkylenesiloxane represented by (5)) was obtained.

[0052]

Embedded image

Next, the following components are kneaded in a kneader,
Heat treatment was performed at a temperature of 120 ° C. for 4 hours.

100 parts by weight of the above polymer fumed silica (specific surface area: 200 m ² / g) 40 {diphenylsilanediol 4} Further, 100 parts by weight of the above kneaded product, 2,5-dimethyl-
2,5-bis (t-butylperoxy) hexane 0.4
Parts by weight using a two-roll mill and uniformly mixing the composition IV
I got

A 2 mm-thick sheet of the composition IV was prepared from this composition IV in the same manner as in the composition I of Example 1.

When the physical properties of the sheets obtained in Examples 3 and 4 were examined, the results shown in Table 2 were obtained.

[0057]

[Table 2]

From the results shown in Table 2, it was confirmed that the silicone rubber composition of the present invention (Examples 3 and 4) gave a cured product having high strength and high tear strength.

Continuing from the front page (72) Inventor Koji Matsuda 1-10 Hitomi, Matsuida-machi, Usui-gun, Gunma Prefecture Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory (56) References JP-A-2-55752 (JP, A)

Claims (2)

(57) [Claims] (A) an organopolysilalkylenesiloxane represented by the following general formula (I): A silicone rubber composition comprising (B) a filler and (C) a curing agent. 2. A cured product obtained by curing the silicone rubber composition according to claim 1.